The Collaborative International Dictionary of English v.0.48:

Gill \Gill\, n. [Abbrev. from Gillian.]
   1. A young woman; a sweetheart; a flirting or wanton girl.
      "Each Jack with his Gill." --B. Jonson.
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   2. (Bot.) The ground ivy (Nepeta Glechoma); -- called also
      gill over the ground, and other like names.
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   3. Malt liquor medicated with ground ivy.
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   Gill ale.
      (a) Ale flavored with ground ivy.
      (b) (Bot.) Alehoof.
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